Relay switching circuit



Feb. 7, 1967 T. E. MYERS RELAY SWITCHING CIRCUIT 2 Sheets-Sheet l FiledJuly L5, 1964 T. E MYERS Feb. 7, 1967 2 Sheets-Sheet Filed July .3, 1964Vil W@ Alw/ i1 4 .a .a

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a0 i? 7 will 7%] United States Patent O 3,303,397 i RELAY SWHTCHING(IIRCUHT Thomas E. Myers, St. harles, Ill., assigner to IdealIndustries, Inc., Sycamore, lil., a corporation of Delaware Filed July13, 1964, Ser. No. 382,332 4 Claims. (Cl. S17-148.5)

' which may be operated with one or more touch surfaces.

Another purpose is a control circuit of the type described utilizing asolid state rectier, preferably a silicon controlled rectifier.

Another purpose is a simplified silicon controlled rectifier circuit foruse in connecting a load to a source of power.

Another purpose is an inexpensive reliably operable touch controlcircuit.

Another purpose is a control circuit of the type described includingrneans to bias the rectifier against stray operation.

Another purpose is a control circuit of the type described includingymeans to remove relay chatter.

Another purpose is a control circuit of the type described utilizing oneor two antennas which actuate the circuit when they receive an electricpotential.

Other purposes will appear in the ensuing specification, drawings andclaims.

The invention is illustrated diagrammatically in the following drawingswherein:

FIGURE 1 is a circuit diagram of one form of control circuit,

FIGURE 2 is a further form of control circuit,

FIGURE 3 is yet a further form of control circuit,

FIGURE 4 is a modified form of control circuit, and

FIGURE 5 is another form of control circuit.

The invention may be described generally as a control circuit suitablefor actuating a relay coil whose contacts perform a control function.The signal for actuating the circuit may come from an antenna. Theantenna mayh'ave a surface positioned for and adapted for human contactso that the potential of the body applied to the antenna is sufficientto operate the circuit. ln the alternative, there may ihe two adjacentantennas positioned such that human contact bridges or shorts the twoantennas together to thereby connect a previously established source ofvolta-ge to operate the circuit. In still another form of operation,human contact at the touch surface may be effective through a momentarycontact shorting arrangement to app-ly a predetermined voltage to anantenna to operate the circuit. Such a circuit would be particularlyuseful when the person contacting the touch surface is wearing gloves.In another form of operation, there may be any number of separa-teantennas positioned at different points, with the application of apotential to any one of these antennas being suficient to operate thecircuit. For example, it may be desirable to turn on an electric lightfrom any one of a `number of different locations. Each location wouldhave an antenna and the antennas would all connect toI a comtmon pointso that the application of a potential to any one of the antennas wouldbe effective to turn on an electric light or perform some other type ofcontrol function. I

In FIGURE l, lines and 12 may be connected to a suitable source ofpower, for example 117 volts A.C., as

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is conventional in home wiring. Line 12 connects to the cathode 14 of asilicon controlled rectifier 16. The anode iti of the rectifier 16 .maybe connected to one side of a coil 2a forming part of a latching relayindicated generally at 22. The other side of the coil 2t) is connectedto line voltage by line lo. Gate 24 of the rectifier 16 may be connectedby a suitable high resistance 26, for example l0 megohms or the like, toa touch surface or antenna indicated diagrammatic-ally at 28. The touchsurface may take any physical form that is satisfactory for humancontact, and in some applications may be remote from the circuitcomponents. It is prefered, although not necessary, to place a biasingresistor 30, which may be variable, between the gate 24 and the cathode14 of rectifier I6. The biasing resistor will be set to insure that therectier 16 is always biased below cut-off.

Relay 22 may have an armature 32 which moves between contacts 34 and35i. Contact 36 is connected to one side of the load and the other sideof the load is connected by a wire 33 to line voltage.

In operation, latching relay 22 will have its armature 32 in contactwith either contact 34 or contact 35. Relay 22, through any suitablemechanical or electrical arrangements not a part of the presentinvention, will hold armature 32 in either one of these two positions.The next time coil 2t? is energized, the armature 32-will move to theother position and will remain in that position until the coil is againenergized. The invention should not be limited to latching or holdingrelays as other types of relays may also be satisfactory. The inventionis directed generally to a control circuit for energizing a relay coil.

The invention works perfectly satisfactorily with a single antenna.However, in some applications, particularly in damp areas of a home, asecond antenna as indicated at at?, is desirable. Antenna 4l? may beconnected by a suitable high resistance 42, again 10 megohms is apractical value, to the anode 18 of the rectifier 16. When two antennasare used, they may me located quite close together.

FIGURE 2 shows a modified control circuit particularly suitable foroperation with a long antenna or connection from the touch surface tothe rectifier. rIhe cathode 14 which in this case may be connected tothe hot side of the line is connected through a biasing resistor 46, adiode 48 and a second biasing resistor Sil to the gate 2d. Resistors 46and 5t) may be either fixed or variable. A portion of the negative halfof the A.C. input will be applied to the gate to prevent operation ofthe rectifier due to a stray Voltage picked up on the lead-in from touchsurface 28. The size of resistors 46 and 50 will be set to compensatefor the length of the lead-in.

The circuit of FIGURE 2 will also work satisfactorily with two antennasin a manner similar to FIGURE 1. A second antenna 52 may be connectedthrough a suitable high resistance 54 to the diode 48.

In FIGURE 3, a coil 56 of a latching relay is connected on one side tocathode 58 of an SCR 60. The anode 62 of t-he rectifier is connected toa set of contacts 64 and 66, there being a relay armature 68 movablebetween these contacts. An antenna 70 is connected to gate 72 of therectifier 6). Although not shown, a suitable high resistance may beplaced between the antenna 70 and the `gate 72. A suitable D.C. sourceis connected to the relay armature 68 and to one side of coil 56. Asecond relay armature 74 is positioned to be movable between contacts 76and 73. It should be noted that relay armatures 74 and 68 are connectedtogether for simultaneous operation.

When antenna 70 receives an electric potential, rectifier 60 willconduct and armature 74 will move from one Contact to the other. Asarmature 74 moves, armature 68 will also move to break the circuitthrough rectifier 60. This has the advantage of momentarily interruptingthe circuit through the SCR to permit it to recover from D C.Isaturation and to cut it off.

In the circuit shown in FIGURES 4 and 5, only the coil of the relay hasbeen illustrated. It should be understood that the contacts of the coilmay be arranged to connect a load and a source in the same manner asshown in FIGURES l and 2, or in any other satisfactory manner.

FIGURES 4 and 5 illustrate a control circuit for operating a relay inwhich the relay coil is connected in a bridge circuit. An SCR Si) mayhave its anode 82 connected to one side of a suitable A.C. source. Thecathode 84 of rectifier 80 may be connected to one terminal of a fullwave bridge rectifier indicated generally at 86. Gate 88 of rectifier 80may be connected through a suitable biasing resistor 90 to termin-al 92of bridge 86. Antennas 94 and 96 are connected through suitableresistances 98 and 190 to the gate 88 and to anode 82 of rectifier 80.Coil 102 of the relay is connected between terminals 92 and 104 of thebridge. As illustrated, there are four diodes indicated at i185 whichmake up the bridge.

Whenever surfaces 94 and 96 are contacted, rectifier 80 will conduct toconnect bridge 86 to the source, Current will always fiow through coil102 in the sa-me direction. This has the advantage of preventing relaychatter. The relay will function like a D.C. relay.

FIGURE is substantially the same as FIGURE 4 'with a single addition. Acurrent limiting resistance 108 and a capacitor 110 are in series acrosscoil 102. The capacitor 110 has the advantage of further removing relaychatter.

The method by which the SCRS are cut off or placed in a non-conductivestate is important. In FIGURES l, 2, 4 and 5, the SCR is cut off becauseof the changed polarity applied by the A.C. source to the anode. In thecircuit of FIGURE 3 the SCR is cut ofi' by breaking the circuit througharmature 68. It is desirable to provide a cut-ofi for the SCR ,as oncethe relay coil has been act-ivated and the armature moved, the switchhas performed its function. The SCR does not have to be placed in aconducting condition until it is desired to again operate the switch.

The use, operation and function of the invention are as follows:

Control circuits of the type described have a variety of applications.One application is in turning lights on and off in the home. The presentcircuits are designed for such an application, but the principlesdisclosed herein are readily applicable to other types of circuits inwhich it is desired to connect a load to a source of power by means ofthe human body touching control surfaces or by means of a potentialbeing applied to an antenna in some other manner. The type of load andthe source of power may vary widely.

When using a single touch surface or antenna, the application of a smallamount of voltage, either A.C. or DC., from the human body 4will apply asignal to the zgate of the silicon controlled rectifier. The gates, inany fof the circuits shown, may be biased below cut-off by .means of asuitable biasing resistor, although this is not necessary. Applicationof a voltage from a single :touch surface will permit the siliconcontrol rectifier to Iconduct and to energize the coil of the relayconnected thereto. Assuming that there is no current to the load, forexample as illustrated in FIGURES l and 2, when the 'coil is energized,the armature will move into a position so as to connect the load to linevoltage. The armature will remain in this position until the antennaagain receives a small potential. The silicon controlled rectifier willagain conduct and the armature will move to the other contact and theload will no longer be connected to line voltage.

The operation of a circuit utilizing two contact surfaces .is somewhatthe same. In order to operate such a circuit,

both surfaces must be contacted by a person at the same time. Theresistors normally in series with the contact surfaces are of asufficient size, for example 10 megohms or the like, to protect theperson contacting the touch surfaces from any possible shock due to linevoltage. Touching of the surfaces provides a signal to the gate of thesilicon controlled rectifier to open the rectifier and permit the coilto be energized. The armature of the relay will then move as described.

When using two t-ouch control surfaces, it is not necessarily thepotential of the body that is applied to the gate. Rather it is thepotential from the line applied through current limiting resistors andthat portion of the body touching the contact surfaces, which iseffective to overcome the negative bias applied to the gate. Forexample, in the circuit of FIGURE l, the gate is positive at the saineperiod as the anode is positive and the silicon controlled rectifierwill conduct. In the circuit of FIGURE 2, the anode is connected to theground side of the line and the silicon controlled rectifier willconduct when the gate is positive and the anode is at ground potential.

In some applications, a further bias may be supplied between the anodeand gate. This bias which may be termed bias to conduct, as against biasto cut off from the cathode, provides increased sensitivity.

Although `a silicon controlled rectifier has been specified, other solidstate rectifiers may also be satisfactory.

The invention should not be limited to operating latching type relays.As can be seen, the particular circuits shown can be utilized toenergize any coil or to operate any type of relay. Both mechanical andelectric or magnetic latching relays may be used.

In any of the circuits shown, the hot side of the line may be connectedto either the anode or cathode of the rectifier. When the cathode isconnected to the hot side, the rectifier is more gate sensitive as thegate has a higher impedance to ground.

Any number of antennas may be connected to the same SCR for operationfrom a variety of remote locations. At each location, the antenna mayreceive a potential from the human body or from momentary contactshorting arrangement.

Whereas the preferred form of the invention has been shown and describedherein, it should be realized that there are many modifications,substitutions yand alterations thereto within the scope of the followingclaims.

I claim:

i. In a control circuit, a control member having contacts for performinga control function, a silicon controlled rectifier having an anode,cathode and gate con nected to a power source, a full wave bridgerectifier connected to said silicon controlled rectifier and said powersource, said control member having a coil connected to oppositeterminals of said bridge rectifier, and the terminals of said bridgerectifier not connected to said coil being connected to said siliconcontrolled rectifier and said source, an antenna and a high resistanceconnection between said antenna and said rectifier gate, a connectionbetween said gate and said coilthe application of an electric potentialto said antenna being effective to provide a signal to the rectifier tocause it to operate.

2. The circuit of claim 1 further characterized by and including asecond antenna and a high resistance connection between said secondantenna and said rectifier.

3. In a contro] circuit for connection to an A.C. source of power, acontrol member having contacts for performing a control function and acoil, a silicon controlled rectifier having an anode and cathodeconnected directly in series with said coil, one side of said rectifierbeing connected directly to the A.C. source and one side of said coilbeing directly connected to the other side of the A.C. source, anantenna arranged for human contact and a high resistance connectionbetween said antenna and the gate of said rectifier, a biasing resistorconnected between the gate and cathode of said rectifier for biasingsaid rectifier below cut-olf, a second antenna arranged for humancontact and a high resistance connection between said second antenna andsaid cathode, human contact with both antennas being effective to applyan operating potential from the A.C. source to the gate to operate therectifier, with said rectier reverting to a cut-olf condition on thenext Ihalf cycle of the A.C. source.

4. The circuit of claim 3 further characterized by a diode in serieswith the biasing resistor connected between the gate and cathode.

2,848,659 8/ 1958 Cutler 317-149 4/1965 Myers S17-151x 15 6 FOREIGNPATENTS 3/ 1963 Canada.

OTHER REFERENCES MILTON O. HIRSHFIELD, Primary Examiner.

MAX L. LEVY, SAMUEL BERNSTEIN, L. T. HIX,

Examiners.

3. IN A CONTROL CIRCUIT FOR CONNECTION TO AN A.C. SOURCE OF POWER, ACONTROL MEMBER HAVING CONTACTS FOR PERFORMING A CONTROL FUNCTION AND ACOIL, A SILICON CONTROLLED RECTIFIER HAVING AN ANODE AND CATHODECONNECTED DIRECTLY IN SERIES WITH SAID COIL, ONE SIDE OF SAID RECTIFIERBEING CONNECTED DIRECTLY TO THE A.C. SOURCE AND ONE SIDE OF SAID COILBEING DIRECTLY CONNECTED TO THE OTHER SIDE OF THE A.C. SOURCE, ANANTENNA ARRANGED FOR HUMAN CONTACT AND A HIGH RESISTANCE CONNECTIONBETWEEN SAID ANTENNA AND THE GATE OF SAID RECTIFIER, A BIASING RESISTORCONNECTED BETWEEN THE GATE AND CATHODE OF SAID RECTIFIER FOR BIASINGSAID RECTIFIER BELOW CUT-OFF, A SECOND ANTENNA ARRANGED FOR HUMANCONTACT AND A HIGH RESISTANCE CONNECTION BETWEEN SAID SECOND ANTENNA ANDSAID CATHODE, HUMAN CONTACT WITH BOTH ANTENNAS BEING EFFECTIVE TO APPLYAN OPERATING POTENTIAL FROM THE A.C. SOURCE TO THE GATE TO OPERATE THERECTIFIER, WITH SAID RECTIFIER REVERTING TO A CUT-OFF CONDITION ON THENEXT HALF CYCLE OF THE A.C. SOURCE.